This application is to design and field the Health and Retirement Study (HRS) and the study of Asset and Health Dynamics Among the Oldest Old (AHEAD) for a six-year period (2000-2005). In 1998, the HRS and AHEAD studies were merged and added two new birth cohorts. The combined study is referred to as the Health and Retirement Study. The HRS was designed to provide a uniquely rich longitudinal dataset for the community of scientific and policy researchers who study the health, economics and demography of aging. The design and execution of the survey has involved the active participation of a large number of scientists from a broad array of disciplines. HRS has evolved considerably from its inception, guided by input from its Steering and Data Monitoring Committees, the broader research community, and scientific review panels that have evaluated earlier proposals. HRS is currently comprised o four birth cohorts: persons born in 1931-41 and their spouses (HRS original cohort); persons born before 1924 and their spouses (AHEAD cohort); and, persons born in 1942-47 ("War Babies") and 1924-30 ("Children of the Depression") and their spouses who were not already included in the original HRS or AHEAD cohorts. We plan to add a new 6-year cohort of Americans entering their 50's in 2004, and every sixth year thereafter. Respondents are followed longitudinally at two-year intervals until they die. In addition to the core biennial interviews, we plan to continue the development of complementary data sources from employer pension plans and from linked administrative data, including Social Security and Medicare records. We will also explore possible linkages associated with geocoding, and employer and nursing home characteristics, as associated with our sample members. In sum, our goals for this period are: l) Continue data collection on the original HRS and AHEAD cohorts; 2) Collect longitudinal data on the new cohorts introduced in 1998; 3) Begin baseline data collection on the "Early Boomer" cohort of 1948-53 in 2004; 4) Continue developing complementary data sources; 5) Enhance data quality; 6) Enhance data distribution and dissemination; 7) Expand outreach activities; and, 8) Continue to innovate content and survey methodology.